[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 181817
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI AUG 18 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE
AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION
IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...
AND METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1745 UTC.

...TROPICAL WAVES...
AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 36W SOUTH OF 20N
MOVING WEST 10 TO 15 KT. ONE MIDDLE TO UPPER LEVEL LOW PRESSURE
CENTER IS NEAR 25N34W. A SECOND LOW CENTER IS NEAR 18N33W. MIDDLE
TO UPPER LEVEL DRY AIR COVERS THE AREA FROM 15N TO 21N BETWEEN
33W AND 40W. ITCZ PRECIPITATION FROM 8N TO 10N BETWEEN 30W AND
36W...AND FROM 9N TO 13N BETWEEN 37W AND 40W DOES NOT APPEAR TO
BE AFFECTED BY THIS WAVE.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 53W/54W SOUTH OF 20N
MOVING WEST 15 KT. A BROAD FIELD OF SURFACE TO LOW LEVEL CLOUDS
AND POSSIBLE SHOWERS COVERS THE WATERS FROM 10N TO 20N BETWEEN
47W AND 60W.

A WESTERN CARIBBEAN SEA TROPICAL WAVE IS ALONG 86W/87W SOUTH
OF 20N MOVING WEST 15 KT. IT DOES NOT APPEAR THAT ANY DEEP
CONVECTIVE PRECIPITATION IS BEING CAUSED BY THIS WAVE.

...THE ITCZ...
ITCZ 14N17W 9N25W 8N35W 10N38W 10N52W 9N55W 8N63W.
SCATTERED TO NUMEROUS STRONG SHOWERS AND THUNDERSTORMS
FROM 6N TO 9N BETWEEN 18W AND 21W. WARMING CLOUD TOP
TEMPERATURES AND DISSIPATING CONVECTIVE ACTIVITY ELSEWHERE
WITHIN 90 TO 120 NM ON EITHER SIDE OF 11N17W 8N19W 4N22W.
WIDELY SCATTERED MODERATE SHOWERS TO ISOLATED STRONG
THUNDERSTORMS WITHIN 30 TO 45 NM ON EITHER SIDE OF 7N27W
8N30W 8N33W 9N37W 11N39W 12N41W 12N45W...AND FROM 10N TO
12N BETWEEN 56W AND 58W. WARMING CLOUD TOP TEMPERATURES
AND DISSIPATING CONVECTIVE ACTIVITY ALONG THE COAST OF
SOUTH AMERICA FROM 7N 11N BETWEEN 58W AND 62W FROM
THE COAST OF GUYANA TO TRINIDAD AND VENEZUELA.

...DISCUSSION...
THE GULF OF MEXICO...
A MIDDLE TO UPPER LEVEL LOW PRESSURE CENTER IS IN THE WEST
CENTRAL GULF WATERS. CYCLONIC FLOW IS WITHIN AT LEAST 240 NM
OF THE CENTER. ISOLATED MODERATE SHOWERS ARE WITHIN 150 NM OF
THE NORTHERN SEMICIRCLE. ISOLATED MODERATE SHOWERS ALREADY HAVE
MOVED ONSHORE FROM NORTHEASTERN MEXICO TO THE MIDDLE TEXAS
COAST. MIDDLE TO UPPER LEVEL CYCLONIC FLOW FROM AN ATLANTIC OCEAN
LOW CENTER NEAR 29N75W IS REACHING PARTS OF NORTHEASTERN AND
EASTERN FLORIDA. SOME OF THE FLOW IS RACING AHEAD OF THE LOW...
TO THE SOUTHWEST AND WEST...AND THEN BECOMES UPPER LEVEL
ANTICYCLONIC FLOW IN THE CENTRAL GULF WATERS. SCATTERED STRONG
SHOWERS AND THUNDERSTORMS IN UPPER LEVEL DIFFLUENT FLOW FROM
6 HOURS AGO IN THE CENTRAL AND NORTH CENTRAL GULF HAS GIVEN WAY
TO WARMING CLOUD TOP TEMPERATURES...AND CONVECTIVE DEBRIS CLOUDS
WITH SOME POSSIBLE LINGERING PRECIPITATION...FROM 24N TO 28N
BETWEEN 86W AND 91W.

THE CARIBBEAN SEA...
A MIDDLE TO UPPER LEVEL LOW CENTER IS IN THE NORTHWESTERN CORNER
OF THE AREA ABOUT HALFWAY IN BETWEEN JAMAICA AND THE WESTERN TIP
OF CUBA. CYCLONIC FLOW AROUND THIS LOW CENTER COVERS THE AREA
BETWEEN EASTERN JAMAICA AND THE YUCATAN PENINSULA NORTH OF 16N.
ISOLATED MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS GO FROM
ABOUT 75 NM WEST OF JAMAICA TO THE COASTAL WATERS OFF CUBA'S
CARIBBEAN SEA COAST NEAR 78W TO THE WESTERN TIP OF CUBA AND
THE YUCATAN CHANNEL. AN UPPER LEVEL ANTICYCLONIC CIRCULATION
CENTER IS NEAR 13N90W JUST WEST OF EL SALVADOR IN THE EASTERN
PACIFIC OCEAN WATERS. ANTICYCLONIC FLOW SPINS AROUND THIS
FEATURE AND MERGES WITH SOME OF THE CYCLONIC FLOW AROUND
THE NORTHWESTERN CORNER LOW CENTER. UPPER LEVEL ANTICYCLONIC
FLOW FROM A COMPLETELY SEPARATE REGIME OF UPPER LEVEL HIGH
PRESSURE IN SOUTH AMERICA MOVES NORTHWARD FROM SOUTH AMERICA
INTO THE SOUTHER HALF OF THE CARIBBEAN SEA...AND THEN EASTWARD.
A MIDDLE TO UPPER LEVEL LOW PRESSURE CENTER IS IN THE ATLANTIC
OCEAN NEAR 25N59W. CYCLONIC FLOW AROUND THIS FEATURE COVERS THE
CARIBBEAN SEA NORTH OF 15N EAST OF 70W. SOME OF THE CYCLONIC
FLOW AROUND THIS LOW CENTER ALSO COMBINES WITH THE FLOW AROUND
THE NORTHWESTERN CARIBBEAN SEA LOW CENTER...THE FLOW AROUND
THE 13N90W HIGH CENTER...AND THE ANTICYCLONIC FLOW FROM SOUTH
AMERICA. HIGH CLOUDS ARE CURVING ACROSS THE EASTERN CARIBBEAN
SEA ISLANDS FROM 13N TO 18N BETWEEN 57W AND 64W. MIDDLE TO
UPPER LEVEL CLOUDS ARE SOUTH OF 15N MOVING TOWARD THE EAST
AND EAST-NORTHEAST. ISOLATED MODERATE SHOWERS AND POSSIBLE
THUNDERSTORMS FROM ITCZ PRECIPITATION ARE SOUTH OF 12N
BETWEEN 74W AND THE COAST OF CENTRAL AMERICA.

THE ATLANTIC OCEAN...
A SURFACE 1013 MB LOW PRESSURE CENTER IS NEAR 30N81W...ABOUT
80 NM EAST OF JACKSONVILLE FLORIDA. UPPER-LEVEL WINDS ARE NOT
CONDUCIVE FOR TROPICAL CYCLONE DEVELOPMENT IN THIS AREA.
SATELLITE AND RADAR DATA INDICATE THAT THE SYSTEM CONTINUES TO
PRODUCE DISORGANIZED SHOWERS AND THUNDERSTORMS WITH BRIEF GUSTY
WINDS. THIS ACTIVITY STILL MAY AFFECT COASTAL AREAS OF GEORGIA
AND THE NORTHERN FLORIDA PENINSULA DURING THE NEXT DAY OR TWO AS
THE SYSTEM MOVES SLOWLY SOUTHWESTWARD. STRONG SHOWERS AND
THUNDERSTORMS ARE OCCURRING FROM 29N TO 31N BETWEEN 79W AND 81W.
A SURFACE TROUGH IS ALONG 31N79W 28N80W. SCATTERED MODERATE
SHOWERS TO ISOLATED STRONG THUNDERSTORMS ARE FOUND FROM 26N TO
29N BETWEEN 69W AND 72W. OTHER ISOLATED MODERATE SHOWERS ARE
NORTH OF 25N BETWEEN 68W AND THE U.S.A. COAST. A WESTERN
ATLANTIC MIDDLE TO UPPER LEVEL LOW PRESSURE CENTER IS NEAR
29N75W. A MIDDLE TO UPPER LEVEL LOW PRESSURE CENTER IS NEAR
32N68W...SOMEWHAT NEAR THE 1018 MB SURFACE LOW CENTER NEAR
32N63W. THE LARGE SCALE 25N59W MIDDLE TO UPPER LEVEL LOW CENTER
COVERS THE ATLANTIC OCEAN WATERS FROM THE CARIBBEAN SEA AT 15N
TO 30N BETWEEN 52W AND 70W. ISOLATED MODERATE SHOWERS AND
POSSIBLE THUNDERSTORMS...SOME DEVELOPING...SOME WEAKENING AND
THEN RE-DEVELOPING IN A SLIGHTLY DIFFERENT LOCATION...ARE FOUND
FROM 20N TO 31N BETWEEN 50W AND 63W. A LARGE SCALE DEEP LAYER
LOW PRESSURE CENTER IS NEAR 36N41W. THE CORRESPONDING SURFACE
1013 MB LOW CENTER IS NEAR 38N43W. A TROUGH GOES FROM THE SURFACE
LOW CENTER TO 37N39W 32N38W 28N40W. POSSIBLE SHOWERS ARE WITHIN
15 NM ON EITHER SIDE OF THE TROUGH. SHOWERS ARE NEAR 33N36W AND
NORTHWARD. AN UPPER LEVEL RIDGE IS ALONG 29W/30W FROM 13N TO
AT LEAST 32N AND BEYOND. ONE TROUGH IS MOVING INTO THE COASTAL
SECTIONS OF NORTHERN MOROCCO. ANOTHER TROUGH IS MOVING TOWARD
THE CANARY ISLANDS.

$$
MT


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